Electromagnet.



0. F. PURSBBRG.

ELTJOTROMAGNET.

APPLICATION FILED AUG.31, 1911 Patented Nov. 17,1914.

WHY/eases.

Any

UNITED STATES PATENT GFFICE.

DSCAR F. FORSBERG, 0F YONKERS, NEW YORK, ASSIGNOR T0 WESTERN ELECTRIC COMPANY, OF NEXV YORK, N. Y., A CORPORATION OF ILLINOIS.

ELECTBQMAGNET.

Specification of Letters Patent.

Patented Nov. 1'7, 1914.

Application filed August 31, 1911. Serial No. 647,039.

To all whomit may concern:

Be it known that I, Oscar: F. FORSBERG, citizen of the United States, residing at Yonkers, in the county of W'estchester and State of New York, have invented certain new and useful Improvement in Electromagnets, of which the following is a full, clear, concise, and exact description.

This invention relates to electromagnets and its principal object is to provide such a structure wherein mechanical work, under loads of extreme variation, may be performed eiiioiently and positively.

To the above end a structure is provided wherein the operating element, after a pre liminary predetermined movement to an intermediate position, picks up its load, and wherein the momentum of the operating element gained during the preliminary movement, supplemented by an increased magnetic attraction, insures positive operation against the greatest mechanical resistance.

This invention will be fully understood from the following description taken in connection with the accompanying drawing in which,

Figure 1 is an elevation, partly in section, showing the magnet with its armature connected to do mechanical work, as in the control of a pay station coin chute or coin collecting apparatus; Figs. 9-, 3 and 4 show the construction and arrangement of the magnet poles, the armature mounting and cooperating parts.

The foundation of the structure comprises a yoke k which may be and. preferably is of soft iron, so as to form an efiioicnt section of the magnetic circuit for the V electromagnetic elements. Secured to the yoke k are two coils 11 formed on soft iron cores c in the usual manner. The ends of cores 0 opposite those adjacent the yoke k have cutaway portions forming pole faces d which materially increase the eiiiciency of the eleotromagnet, as will be hereinafter explained. Near the pole faces 0! the cores 0 are interconnected by and support a bridge y, which is provided with two upturned projections 5 between and to which the armaturestructure, to be hereinafter described, is pivotally mounted.

The armature structure comprises a sup port 10 of non-magnetic metal provided with downwardly projecting ears 11. The

ears 11 are perforated or indented to receive the points of trunnion screws 12 thus forming a pivotal bearing, about which the support 10 may be rotated. Support 10 is also provided with elongated openings 13, 14 and 15. The longer axes of openings 13 and 15 are in a. line substantially per- ,endicular to the axial line of support 10, while the axis of opening 15 is parallel to the axial line of support 10, for a. purpose which will now be explained. An armature a is adjustably held to the support 10 by clamping screws 77, which project therethrough and thread into the armature a. An adjusting screw 78 with an eccentrically formed head, which rests within the opening 14, also threads into the armature a. It will, therefore, be readily understood that when screws 77 are loosened, the turning of adjusting screw 78 will move the armature a. in a direction transverse to the axis of its support 10. The tightening of screws 77 will hold the armature firmly in position. By these means the location of the armature a, relative to the pole faces d;

to rotate in either direction, may move.

freely through a small angle before engaging one of the projections 85.. Plate 80 is likewise supplied at each end with a. downwardly projecting arm 95, adapted when the armature a is rotated to engage the bridge 1/ to limit such rotary movement. One of the cars 81 of plate 80 is elongated and forked, as shown, and may be suitably connected to any desired mechanical move-- ment. In the preferred embodiment disclosed the fork of elongated ear 81 engages "105 and is adapted to move a. rod 9 of a coin distributing mechanism f.

Means are provided to normally hold the armature in a neutrr-i position relative to the pole faces of, and to return the armature to 110 able levers 82 and 83, likewise pivotally mounted on trunnion screws 12. Each of these levers is provided with a small prepaction 84 adapted to be engaged by the plate 80 and thereby communicate the motion of armature.

armature a to either lever 82 or 83,depending upon the direction of rotation of the Thus when the armature moves in a clockwise direction, it carries with it only the lever 82, while if the rotation of the armature is in the reverse direction, only lever 83 will be moved thereby. The construction, whereby a small projection, such as 84, communicates motion from plate to either lever 82 or 83, reduces the sliding friction, while the armature is being rotated, and is therefore a factor in increasing the efiiciency of the entire. structure. Levers 82 and 83 are provided with downwardly extending arms 91 and 92 respec- ,tively, which normally rest against the tops of the cores 0 because of the tensionof springs 89 which are connected at one end to the framework and'at the other end to levers 82 and 83, as shown. It is therefore readily apparent that armature a is norinally yieldingly held in a neutral position relative to the pole faces d, and is positively l and accurately returned to this position after i. has been displaced and the coils b have become deenergized. "An arm 17 extending from plate 80, may be employed to control the engagement of contact springs, such as 18 and 19, which are joined to current-carrying leads 20, and a permanent magnet p may be secured to the ydke la and extend beside the cells I), as shown. I

In operation the coils b may be energized to deflect the armature a in either direction. Upon such energization the preliminary movement of armature a, due to the formation of pole faces d, causes a relatively great decrease in the airgap between the depressed end of armature a and the cobperat ing pole face d, and a corresponding increase in the air-gap between the other end of the armature and its cooperating pole face. Thus, the magnetic attraction is greatly augmented and the operative force exerted by the armature is materially increased. Due to the space between the projections 85 and armature a, the armature makes this pre liminary movement and so increases the effect of the magnetic field, as above explained, before the load joined to ear 81 is picked up. When armature a engages one of the projections 85, plate 80 rotates about trunnion screws 12, resulting in a rotary movement of one of the levers 82 or 83 and the operation of contact springs 18 and 19 by means of projection 17. The movement of plate 80 and consequently or armature a and lever 82 or 88 is regulated and checked by the engagement of one of the arms 91 or 92 with the yoke 34. hen the current.

ceases to flow through coils b, springs 89 return the displaced lever 82 or 83 until its arm 91 or 92 engages the pole of its correspending core 0, whereupon the apparatus,

ported on the armature pivots and adapted to be singly and selectively actuated by said armature, and means for communicating motion from said armature to said levers.

and to limit the movement thereof.

2. An electromagnet comprising a pair of coils, a bridge therefor, an armature pivot ed to said bridge,- a plate supported on the armature pivots and movable by said armature, and a pair of spring tensioned levers:

supported on the armature pivots and adapt ed to gradually increase the load on said.

armature during its movement.

t). An electromagnet comprising a pair of" cpils, a bridge therefor, an armature pivoted, to said bridge, a plate supported on the armature pivots and movable by said armature after a preliminary movement thereof, two levers likewise su ported on the armature pivots and mova le by said armature, and a retractile spring for each of said levers.

4. An electromagnet comprising a pair of coils, a bridge therefor, a pivoted armature for said coils, a plate supported'on the armature pivots and spaced from said armature to be moved thereby only after a preliminary movement thereof, and means carried by said plate to limit the movement of said armature by engagement with said bridge.

5. An electromagnet comprising a pair of coils, a pivoted armature therefor, a plate supported on the armature pivots and spaced from said armature to be moved thereby only-after a preliminary movement thereof to limit the movement of said armature, and a pair of spring tensioned levers likewise supported on the armature pivots and movable by said armature and adapted to gradually increase the load carried thereby.

In witness whereof, I hereunto subscribe my name this 30th day of August A. 1).,

OSCAR F. FORSBERG. lrVitnesses Invnvo MacDoNaLD, MoReAN ViasHeosN, J r. 

